A footman is a servant who works in a large, wealthy home. There aren't many footmen left these days, although you can still find some working for the British royal family.
It was once common for wealthy families to employ uniform-wearing male servants. These footmen, usually young men, served food at the dinner table, filled in for absent butlers, carried heavy things, and opened and closed doors. The word footman comes from the original job of a running footman — an agile servant would run beside his master's carriage making sure it didn't tip over. Earlier, a footman was a "soldier who travels on foot," rather than on horseback.